Deep wide pits (about 5 mm in size) are diagnostic of psoriasis.
Smaller pits are likely of no importance as far as known and a whole list of diseases has been compiled by many writers who probably profusely copied from each other without ever have seen such diseases
Jokingly this has been called “scholarship” by Shapira

Orient, Jane M.. Sapira’s Art and Science of Bedside Diagnosis . Lippincot (Wolters Kluwer Health). Kindle Edition.